22 research outputs found

    Directional takeoff, aerial righting, and adhesion landing of semiaquatic springtails

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    Springtails (Collembola) have been traditionally portrayed as explosive jumpers with incipient directional takeoff and uncontrolled landing. However, for these collembolans who live near the water, such skills are crucial for evading a host of voracious aquatic and terrestrial predators. We discover that semiaquatic springtails Isotomurus retardatus can perform directional jumps, rapid aerial righting, and near-perfect landing on the water surface. They achieve these locomotive controls by adjusting their body attitude and impulse during takeoff, deforming their body in mid-air, and exploiting the hydrophilicity of their ventral tube, known as collophore. Experiments and mathematical modeling indicate that directional-impulse control during takeoff is driven by the collophores adhesion force, the body angle, and the stroke duration produced by their jumping organ, the furcula. In mid-air, springtails curve their bodies to form a U-shape pose, which leverages aerodynamic forces to right themselves in less than 20 ms, the fastest ever measured in animals. A stable equilibrium is facilitated by the water adhered to the collophore. Aerial righting was confirmed by placing springtails in a vertical wind tunnel and through physical models. Due to these aerial responses, springtails land on their ventral side 85% of the time while anchoring via the collophore on the water surface to avoid bouncing. We validated the springtail biophysical principles in a bioinspired jumping robot that reduces in-flight rotation and lands upright 75% of the time. Thus, contrary to common belief, these wingless hexapods can jump, skydive and land with outstanding control that can be fundamental for survival.Comment: 12 pages, 8 figure

    Advances in Bio-Inspired Robots

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    This book covers three major topics, specifically Biomimetic Robot Design, Mechanical System Design from Bio-Inspiration, and Bio-Inspired Analysis on A Mechanical System. The Biomimetic Robot Design part introduces research on flexible jumping robots, snake robots, and small flying robots, while the Mechanical System Design from Bio-Inspiration part introduces Bioinspired Divide-and-Conquer Design Methodology, Modular Cable-Driven Human-Like Robotic Arm andWall-Climbing Robot. Finally, in the Bio-Inspired Analysis on A Mechanical System part, research contents on the control strategy of Surgical Assistant Robot, modeling of Underwater Thruster, and optimization of Humanoid Robot are introduced

    The jumping mechanism of flea beetles (Coleoptera, Chrysomelidae, Alticini), its application to bionics and preliminary design for a robotic jumping leg

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    Flea beetles (Coleoptera, Chrysomelidae, Galerucinae, Alticini) are a hyperdiverse group of organisms with approximately 9900 species worldwide. In addition to walking as most insects do, nearly all the species of flea beetles have an ability to jump and this ability is commonly understood as one of the key adaptations responsible for its diversity. Our investigation of flea beetle jumping is based on high-speed filming, micro- CT scans and 3D reconstructions, and provides a mechanical description of the jump. We reveal that the flea beetle jumping mechanism is a catapult in nature and is enabled by a small structure in the hind femur called an ‘elastic plate’ which powers the explosive jump and protects other structures from potential injury. The explosive catapult jump of flea beetles involves a unique ‘high-efficiency mechanism’ and ‘positive feedback mechanism’. As this catapult mechanism could inspire the design of bionic jumping limbs, we provide a preliminary design for a robotic jumping leg, which could be a resource for the bionics industry

    Inherently Elastic Actuation for Soft Robotics

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    Liquid notations:A common language of transitions

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    If we lived in a liquid world, the concept of a "machine" would make no sense. Liquid life is metaphor and apparatus that discusses the consequences of thinking, working, and living through liquids. It is an irreducible, paradoxical, parallel, planetary-scale material condition, unevenly distributed spatially, but temporally continuous. It is what remains when logical explanations can no longer account for the experiences that we recognize as part of "being alive."Liquid Life references a third-millennial understanding of matter that seeks to restore the agency of the liquid soul for an ecological era, which has been banished by reductionist, "brute" materialist discourses and mechanical models of life. Offering an alternative worldview of the living realm through a "new materialist" and "liquid" study of matter, Armstrong conjures forth examples of creatures that do not obey mechanistic concepts like predictability, efficiency, and rationality. With the advent of molecular science, an increasingly persuasive ontology of liquid technologies can be identified. Through the lens of lifelike dynamic droplets, the agency for these systems exists at the interfaces between different fields of matter/energy that respond to highly local effects, with no need for a central organizing system.Liquid Life seeks an alternative partnership between humanity and the natural world. It provokes a re-invention of the languages of the living realm to open up alternative spaces for exploration, including contributor Rolf Hughes’ "angelology" of language, which explores the transformative invocations of prose poetry, and Simone Ferracina’s graphical notations that help shape our concepts of metabolism, upcycling, and designing with fluids. A conceptual and practical toolset for thinking and designing, liquid life reunites us with the irreducible "soul substance" of living things, which will neither be simply "solved," nor go away

    Investigating Energetic Porous Silicon as a Solid Propellant Micro-Thruster

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    Energetic porous silicon has emerged as a novel on-chip energetic material capable of generating thrust that can be harnessed for positioning of millimeter and micron-scale mobile platforms such as microrobots and nano-satellites. Porous silicon becomes reactive when nano-scale pores are infused with an oxidizer such as sodium perchlorate. In this work, energetic porous silicon was investigated as a means of propulsion by quantifying thrust and impulse produced during the exothermic reaction as a function of porosity. The baseline porous silicon devices were two millimeter diameter and etched to a target depth of 25 microns. As a result of changing porosity, a 7x increase in thrust performance and a 16x increase in impulse performance was demonstrated. The highest thrust and impulse values measured were 680 mN and 266 micron Newton seconds respectively from a 2 mm diameter porous silicon device with 72 % porosity. Limitations and trade-offs associated with arrays of devices were presented by studying the effects of scaling porous silicon area, and characterizing thrust when arrays of porous silicon micro-thruster devices were ignited simultaneously. In addition, the effects of sympathetic ignition were evaluated to better understand how closely independent devices could be physically spaced on a 1 cm2 chip. 3D nozzles were fabricated to study confinement effects by varying nozzle throat diameter, and divergent angle. It was shown that integration of a nozzle (throat diameter of 0.75 mm and a divergent angle of theta = 10 degrees) resulted in approximately 4X increase in thrust, and 4X increase in impulse. This study highlighted enhancements to thrust and impulse generated by porous silicon, identified trade-offs associated with simultaneous activation of multiple devices on a 1 cm2 chip, and showed energetic porous silicon as a viable solid propellant for propulsion of nano-satellites and micro-robots

    Affordances And Control Of A Spine Morphology For Robotic Quadrupedal Locomotion

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    How does a robot\u27s body affect what it can do? This thesis explores the question with respect to a body morphology common to biology but rare in contemporary robotics: the presence of a bendable back. In this document, we introduce the Canid and Inu quadrupedal robots designed to test hypotheses related to the presence of a robotic sagittal-plane bending back (which we refer to as a ``spine morphology\u27\u27). The thesis then describes and quantifies several advantages afforded by this morphological design choice that can be evaluated against its added weight and complexity, and proposes control strategies to both deal with the increase in degrees-of-freedom from the spine morphology and to leverage an increase in agility to reactively navigate irregular terrain. Specifically, we show using the metric of ``specific agility\u27\u27 that a spine can provides a reservoir of elastic energy storage that can be rapidly converted to kinetic energy, that a spine can augment the effective workspace of the legs without diminishing their force generation capability, and that -- in cases of direct-drive or nearly direct-drive leg actuation -- the spine motors can contribute more work in stance than the same actuator weight used in the legs, but can do so without diminishing the platform\u27s proprioceptive capabilities. To put to use the agility provided by a suitably designed robotic platform, we introduce a formalism to approximate a set of transitional navigational tasks over irregular terrain such as leaping over a gap that lend itself to doubly reactive control synthesis. We also directly address the increased complexity introduced by the spine joint with a modular compositional control framework with nice stability properties that begins to offer insight into the role of spines for steady-state running. A central theme to both the reactive navigation and the modular control frameworks is that analytical tractability is achieved by approximating the modes driving the environmental interactions with constant-acceleration dynamics

    Multiscale methods for fabrication design

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    Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 135-146).Modern manufacturing technologies such as 3D printing enable the fabrication of objects with extraordinary complexity. Arranging materials to form functional structures can achieve a much wider range of physical properties than in the constituent materials. Many applications have been demonstrated in the fields of mechanics, acoustics, optics, and electromagnetics. Unfortunately, it is difficult to design objects manually in the large combinatorial space of possible designs. Computational design algorithms have been developed to automatically design objects with specified physical properties. However, many types of physical properties are still very challenging to optimize because predictive and efficient simulations are not available for problems such as high-resolution non-linear elasticity or dynamics with friction and impact. For simpler problems such as linear elasticity, where accurate simulation is available, the simulation resolution handled by desktop workstations is still orders of magnitudes below available printing resolutions. We propose to speed up simulation and inverse design process of fabricable objects by using multiscale methods. Our method computes coarse-scale simulation meshes with data-drive material models. It improves the simulation efficiency while preserving the characteristic deformation and motion of elastic objects. The first step in our method is to construct a library of microstructures with their material properties such as Young's modulus and Poisson's ratio. The range of achievable material properties is called the material property gamut. We developed efficient sampling method to compute the gamut by focusing on finding samples near and outside the currently sampled gamut. Next, with a pre-computed gamut, functional objects can be simulated and designed using microstructures instead of the base materials. This allows us to simulate and optimize complex objects at a much coarser scale to improve simulation efficiency. The speed improvement leads to designs with as many as a trillion voxels to match printer resolutions. It also enables computational design of dynamic properties that can be faithfully reproduced in reality. In addition to efficient design optimization, the gamut representation of the microstructure envelope provides a way to discover templates of microstructures with extremal physical properties. In contrast to work where such templates are constructed by hand, our work enables the first computational method to automatically discovery microstructure templates that arise from voxel representations.by Desai Chen.Ph. D

    Observing and modelling the legless jumping mechanism of click beetles for bio-inspired robotic design

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    Click beetles (Coleoptera: Elateridae) have evolved a unique jumping mechanism to right themselves when on their dorsal side without using their legs or any other appendages. This work describes and analyzes the stages of the click beetle jump using high-speed video recordings and scanning electron micrographs of six beetle species, namely Alaus oculatus, Ampedus linteus, Hemicrepidius sp., Melanactes sp., Melanotus spp. and Parallelosthetus attenuatus. The jump of the click beetle is divided into three consecutive stages: the pre-jump stage (energy storage), and the take-off and airborne stages (energy release). Morphological measurements of the previously mentioned species as well as three additional species, namely Agriotes sp., Athous sp. and Lacon discoideus are taken, and isometric scaling across the species is observed. The body of the click beetle is considered as two masses linked by a hinge. Dynamic and kinematic models of the jump stages are developed. Non-dimensional analysis of the airborne stage is used to analyze the jump and identify the contribution of kinematic and morphological governing parameters. An energetics model is developed to describe the energy exchanges between the three stages of the jump. Kinematic and dynamic models are used to calculate the hinge stiffness and the elastic energy stored in the body during the jump. The derived models provide a framework that will be used for the design of a click beetle inspired self-righting robot
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